Gradual Changes in Computing FocusEarly Computing Focused on Operational RequirementsDecisional Requirements Cannot Be Fully AnticipatedOperational Systems Fail to Provide Decisional InformationDecisional Systems Have Evolved to Meet Decisional RequirementsThe Data Warehouse DefinedIntegratedSubject OrientedDatabasesRequired for Decision-MakingEach Unit of Data Is Relevant to a Point in TimeA Data Warehouse Contains Both Atomic and Summarized DataThe Dynamic, Ad Hoc ReportThe Purposes of a Data WarehouseTo Provide Business Users with Access to DataTo Provide One Version of the TruthTo Record the Past AccuratelyTo Slice and Dice Through DataTo Separate Analytical and Operational ProcessingTo Support the Reengineering of Decisional ProcessesA Word About Data MartsMisconception: Data Warehouses and Data Marts Cannot CoexistMisconception: Data Marts Can Be Built Independently of One AnotherA Word About Operational Data StoresDefinition of Operational Data StoresFlash Monitoring and Reporting ToolsRelationship of Operational Data Stores to Data WarehouseData Warehouse Cost-Benefit Analysis / Return on InvestmentBenefitsCostsROI ConsiderationsIn Summary